Ministers have been urged to pump more money into student grants and loans or risk missing their target for getting 50 per cent of young people into university.

Funding chiefs and student leaders warned that without extra investment, the Government's aims were in danger of being undermined as students are faced with huge debts for top-up fees.

Sir Howard Newby, chief executive of the Higher Education Funding Council for England (Hefce), said Ministers faced a crucial decision about future funding of financial support for students.

And the National Union of Students (NUS) challenged the Government to "put its money where its mouth is" and come up with generous grants.

Last week, Sir Howard warned that a "considera-ble" rise in student numbers would be needed if Ministers were to reach Tony Blair's target to get 50 per cent of 18- to 30-year-olds into higher education by 2010.

Sir Howard said: "Unless increased funding is made available for student support there is a danger that the major constraint on achieving the 50 per cent target would be student-support funding.

"There's all to play for in the next spending review and the extent to which the Treasury will give priority to achieving that target." NUS vice president for education Hannah Essex, warned that any further uncertainty over student support could deter poor teenagers from applying to university.

"Instead of simply paying lip service to its access agenda, the Government needs to put its money where its mouth is and start properly investing in higher education," she said.

Next week will see the announcement of the first set of agreements between the Government's new university access watchdog - the Office for Fair Access - and individual universities.

Reaching such an "ac-cess agreement" is compulsory for any university that wants to charge topup tuition fees of up to £3,000 a year from 2006.

As part of these agree-ments, universities are expected to announce bursaries to attract students from poorer backgrounds to stop them being put off by the higher fees.

A spokeswoman for the Department for Education and Skills insisted the Government was making "steady progress" towards the 50 per cent target.

"For 2002/03, 44 per cent of 18 to 30-year-olds were in higher education and there has been an increase of one percentage point a year for the last four years," she said.